Low tidal volume pressure support versus controlled ventilation in early experimental sepsis in pigs

Abstract

BackgroundIn moderate acute respiratory distress syndrome (ARDS) several studies support the usage of assisted spontaneous breathing modes. Only limited data, however, focus on the application in systemic sepsis and developing lung injury. The present study examines the effects of immediate initiation of pressure support ventilation (PSV) in a model of sepsis-induced ARDS.Methods18 anesthetized pigs received a two-staged continuous lipopolysaccharide infusion to induce lung injury. The animals were randomly assigned to PSV or volume controlled (VCV) lung protective ventilation (tidal volume each 6 ml kg-1, n = 2x9) over six hours. Gas exchange parameters, hemodynamics, systemic inflammation, and ventilation distribution by multiple inert gas elimination and electrical impedance tomography were assessed. The post mortem analysis included histopathological scoring, wet to dry ratio, and alveolar protein content.ResultsWithin six hours both groups developed a mild to moderate ARDS with comparable systemic inflammatory response and without signs of improving gas exchange parameters during PSV. The PSV group showed signs of more homogenous ventilation distribution by electrical impedance tomography, but only slightly less hyperinflated lung compartments by multiple inert gas elimination. Post mortem and histopathological assessment yielded no significant intergroup differences.ConclusionsIn a porcine model of sepsis-induced mild ARDS immediate PSV was not superior to VCV. This contrasts with several experimental studies from non-septic mild to moderate ARDS. The present study therefore assumes that not only severity, but also etiology of lung injury considerably influences the response to early initiation of PSV.

Use of perfusion index to detect hemodynamic changes in endotoxemic pigs

“…Previous studies used higher doses of LPS (100 μg/kg/h for 1 h followed by 10 μg/kg/h) to create acute respiratory distress syndrome (ARDS) in pigs 34 . The pigs in the current study did not develop pulmonary edema or decompensatory shock, despite transient changes in ELWI and Pa o 2 .…”

Pulmonary effects of expiratory‐assisted small‐lumen ventilation during upper airway obstruction in pigs

“…This study has several limitations. We chose a convenient sample of eight animals for SLV that was based on previous publications making use of comparable animal models and monitoring technologies – there were no preceding in‐vivo data to conduct a proper power analysis. Continuous performance of manual SLV over 30 min by a single person is difficult, and will almost certainly lead to interruptions or dyssynchrony of ventilation.…”

“…Extended respiratory monitoring included electrical impedance tomography (Goe‐MF II, CareFusion) to measure changes of the thoracic bioimpedance associated with pulmonary aeration in three pulmonary levels (non‐dependent, central and dependent) . We assessed the ventilation/perfusion (V A /Q) distribution by perfusion‐based micropore membrane inlet mass spectrometry – multiple inert gas elimination technique (MMIMS‐MIGET, Oscillogy LLC, Folsom, PA, USA) .…”

“…The lung samples were fixed in formalin for paraffin embedding, and stained using haematoxylin/eosin dye. A standardised scoring system was used for the evaluation , which was based on the diffuse alveolar damage score .…”

Peer Review #2 of "Random allogeneic blood transfusion in pigs: characterisation of a novel experimental model (v0.1)"

“…In case of respiratory insufficiency, mechanical ventilation parameters escalated according to an adaption of the ARDS network tables. (Ziebart et al 2014 Manuscript to be reviewed transpulmonary thermodilution-derived parameters, spirometry, and gas exchange were continuously monitored (Datex S/5 Monitor, GE Healthcare, Germany; PiCCO, Pulsion Medical Systems, Germany). Hematological and blood gas measurements were repetitively conducted.…”